using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using GammaJul.ForTea.Core.Psi.Cache;
using GammaJul.ForTea.Core.Tree;
using JetBrains.Annotations;
using JetBrains.Application.Parts;
using JetBrains.Application.Threading;
using JetBrains.DataFlow;
using JetBrains.Diagnostics;
using JetBrains.Interop.WinApi;
using JetBrains.Lifetimes;
using JetBrains.ProjectModel;
using JetBrains.ReSharper.Psi;
using JetBrains.ReSharper.Psi.Caches;
using JetBrains.Util;
using JetBrains.VsIntegration.ProjectModel;
using Microsoft.VisualStudio.Shell.Interop;

namespace JetBrains.ForTea.ReSharperPlugin.Psi.Resolve.Macros
{
  /// <summary>
  /// In R#, it is only possible to resolve macros on the main thread,
  /// so we have to cache them to be able to access them from the daemon
  /// </summary>
  [PsiComponent(InstantiationEx.LegacyDefault)]
  public sealed class T4MacroResolutionCache : T4PsiAwareCacheBase<T4MacroResolutionRequest, T4MacroResolutionData>
  {
    [NotNull] public Signal<IPsiSourceFile> OnFileMarkedForInvalidation { get; }

    public T4MacroResolutionCache(
      Lifetime lifetime,
      [NotNull] IShellLocks locks,
      [NotNull] IPersistentIndexManager persistentIndexManager,
      [NotNull] ISolution solution
    ) : base(lifetime, locks, persistentIndexManager, T4MacroResolutionDataMarshaller.Instance) =>
      OnFileMarkedForInvalidation = new(lifetime, "Update from T4MacroResolutionCache");

    [NotNull]
    protected override T4MacroResolutionRequest Build(IT4File file)
    {
      var macros = file
        .GetThisAndChildrenOfType<IT4Macro>()
        .Where(macro => macro.RawAttributeValue != null)
        .Distinct(macro => macro.RawAttributeValue.GetText());
      return new T4MacroResolutionRequest(macros.ToList());
    }

    public override void Merge(IPsiSourceFile sourceFile, object builtPart)
    {
      var request = (T4MacroResolutionRequest)builtPart.NotNull();
      var projectFile = sourceFile.ToProjectFile().NotNull();
      var macroNames = request.MacrosToResolve.Select(macro => macro.RawAttributeValue.GetText());
      var oldKeys = Map.TryGetValue(sourceFile)?.ResolvedMacros.Keys ?? EmptyList<string>.Instance;
      var data = new T4MacroResolutionData(ResolveHeavyMacros(macroNames, projectFile));
      var newKeys = data.ResolvedMacros.Keys;
      base.Merge(sourceFile, data);

      if (!newKeys.All(it => oldKeys.Contains(it)))
      {
        OnFileMarkedForInvalidation.Fire(sourceFile);
      }
    }

    [CanBeNull]
    public T4MacroResolutionData TryGetValue(IPsiSourceFile sourceFile)
    {
      base.TryGetValue(sourceFile, out var value);
      return value;
    }

    [NotNull]
    private IReadOnlyDictionary<string, string> ResolveHeavyMacros(
      [NotNull] IEnumerable<string> macros,
      [NotNull] IProjectFile file)
    {
      var result = new Dictionary<string, string>();
      Lazy<IVsBuildMacroInfo> vsBuildMacroInfo = Lazy.Of(() => TryGetVsBuildMacroInfo(file), false);
      foreach (string macro in macros)
      {
        bool succeeded = false;
        string value = null;
        if (vsBuildMacroInfo.Value != null)
        {
          succeeded = HResultHelpers.SUCCEEDED(vsBuildMacroInfo.Value.GetBuildMacroValue(macro, out value)) &&
                      !string.IsNullOrEmpty(value);
        }

        if (!succeeded)
        {
          value = MSBuildExtensions.GetStringValue(T4ResolutionUtils.TryGetVsHierarchy(file), macro, null);
          succeeded = !string.IsNullOrEmpty(value);
        }

        if (succeeded)
        {
          result[macro] = value;
        }
      }

      return result;
    }

    /// <summary>
    /// The <see cref="IVsHierarchy"/> representing the project file
    /// normally implements <see cref="IVsBuildMacroInfo"/>.
    /// </summary>
    /// <returns>An instance of <see cref="IVsBuildMacroInfo"/> if found.</returns>
    [CanBeNull, SuppressMessage("ReSharper", "SuspiciousTypeConversion.Global")]
    private static IVsBuildMacroInfo TryGetVsBuildMacroInfo([NotNull] IProjectFile file) =>
      T4ResolutionUtils.TryGetVsHierarchy(file) as IVsBuildMacroInfo;
  }
}